Ask a Trainer: How Do I Train for a Marathon as a Triathlete?

As the fall months progress and the triathlon season begins to draw to a close, many triathletes find themselves looking for the next challenge. Along with cooler, more running-friendly temperatures comes a plethora of marathon options in winter and spring. Thankfully, a summer spent triathlon training lends itself nicely to training for an early-season marathon. With a few tweaks and changes in focus points, a marathon training plan for triathletes can build toward a solid offseason marathon while still keeping some of the balance provided by swimming and biking. If you’re a triathlete taking on an open marathon during your offseason, here’s how your training plan will change.

More running

This one is obvious, but let’s dive a little deeper into what this might look like in a marathon training plan for triathletes. While triathlon training is great for building aerobic endurance, marathon running will require more specific muscular endurance, particularly the ability to handle eccentric muscle contractions for miles upon miles.

Triathletes focused on marathon performance should aim for two quality run sessions per week to increase marathon-specific fitness, with 2-3 shorter to moderate-length, recovery or easy aerobic runs to build run durability. The structure of quality sessions can vary, but common examples include long runs with portions done at goal marathon pace (be realistic!), and moderate-length workouts with intervals done at 5K or tempo pace. Still, because you’re following a marathon training plan for triathletes, you’ll have some swimming and biking or recovery and aerobic work. Therefore, weekly mileage does not need to be as high as in traditional run-only marathon training.

Ride to complement your runs

Although running takes precedence when marathon training, biking can still play a strong supporting role in a triathlete’s marathon training plan. Rides provide added aerobic stimulus and endurance without the impact-related risks of straight run mileage.

During this time, top-end, ultra high-intensity riding is not the priority, as the added run volume and intensity will take the edge off of your bike legs. Remember, the body should not be too tired from bike efforts to hit key run workouts. Triathletes should not expect to maintain peak bike fitness while training for an offseason marathon, but 2-3 shorter to moderate (1-3 hour or so) length rides at easy aerobic to tempo intensities will assist aerobic adaptations and maintain some bike fitness without detracting from the focus discipline of running.

Swim for recovery and technique

Finally, swimming. The fatigue from increased run training tends to be deleterious to swimming, so the focus in the pool while marathon training should be assisting with active recovery while maintaining some feel for the water. Pull buoy use and technique work are encouraged in order to keep the upper body engaged and assist with soft tissue recovery without undue frustration. Swim frequency can vary based on individual athlete desires, strengths, and time constraints, but 1-3 swims per week will help to both support marathon training and recovery, and maintain familiarity with the water in order to regain swim fitness more easily once the run focus is over.

With a few alterations in training to add in a greater proportion of run volume and intensity, triathletes (and their aerobic engines) are set up well to cap off their seasons with a standalone marathon. Many have found fun and success by taking on a similar yet different offseason challenge.